Lens assembly

Abstract

A lens assembly includes a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, and a reflective element. The first lens group is with positive refractive power. The second lens group is with negative refractive power. The third lens group is with positive refractive power. The fourth lens group is with negative refractive power. The fifth lens group is with positive refractive power. The reflective element includes a reflective surface. A light from an object side sequentially passes through the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group to a second side. The reflective element is disposed between a first side and the second side. Intervals of the lens groups are changeable, so that the lens assembly can change the effective focal length.

What is claimed is: 
     
       1. A lens assembly comprising:
 a first lens group which is with positive refractive power; 
 a shading element; 
 a second lens group which is with negative refractive power; 
 a third lens group which is with positive refractive power; 
 a fourth lens group which is with negative refractive power; 
 a fifth lens group which is with positive refractive power; and 
 a reflective element which comprises a reflective surface; 
 wherein the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group are arranged in order from a first side to a second side along an axis; 
 wherein a light from an object side sequentially passes through the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group to the second side; 
 wherein the shading element comprises a variable hole and the variable hole is a non-circular hole; 
 wherein the reflective element is disposed between the first side and the second side; 
 wherein intervals of the lens groups are changeable, so that the lens assembly can change the effective focal length. 
 
     
     
       2. The lens assembly as claimed in  claim 1 , wherein the shading element disposed between the first lens group and the second lens group. 
     
     
       3. The lens assembly as claimed in  claim 2 , wherein the variable hole can change dimension according to the effective focal length of the lens assembly. 
     
     
       4. The lens assembly as claimed in  claim 1 , wherein at least one lens of the lens groups has different effective optical diameters in the short side direction and in the long side direction. 
     
     
       5. The lens assembly as claimed in  claim 4 , wherein the third lens group comprises a plurality of lenses and some of the lenses can be moved perpendicular to the direction perpendicular to the axis to achieve optical image stabilization. 
     
     
       6. The lens assembly as claimed in  claim 4 , wherein the reflective element is disposed between the first side and the first lens group and the fourth lens group can move along the axis to perform focusing. 
     
     
       7. The lens assembly as claimed in  claim 1 , wherein the second lens group, the fourth lens group, and the fifth lens group can move along the axis and the first lens group and the third lens group are fixed to change intervals of the lens groups, so that the lens assembly can change the effective focal length. 
     
     
       8. A lens assembly comprising:
 a first lens group which is with positive refractive power; 
 a second lens group which is with negative refractive power; 
 a stop; 
 a third lens group which is with positive refractive power; 
 a fourth lens group which is with negative refractive power; 
 a fifth lens group which is with positive refractive power; and 
 a reflective element which comprises a reflective surface; 
 wherein the first lens group, the second lens group, the stop, the third lens group, the fourth lens group, and the fifth lens group are arranged in order from a first side to a second side along an axis; 
 wherein a light from an object side sequentially passes through the first lens group, the second lens group, the stop, the third lens group, the fourth lens group, and the fifth lens group to the second side; 
 wherein the reflective element is disposed between the first side and the second side; 
 wherein intervals of the lens groups are changeable, so that the lens assembly can change the effective focal length; 
 wherein the reflective element further comprises an incident surface and an exit surface and both of which are connected to the reflective surface; 
 wherein the incident surface faces the object side along the direction perpendicular to the axis; 
 wherein the exit surface faces the second side along the axis; and 
 the lens assembly satisfies at least one of following conditions:
   0.5 mm< EPA/PL< 5.5 mm; 
   0.7 mm< EPA/STD< 10 mm; 
   0.2< EPDX/STD< 2.1; 
   0< EPDY/STD< 1.5; 
   0.8< PL/EPDX< 4; 
   0.7< PH/EPDY< 3; 
   −1.1< f 2/ fW<− 0.3;
 
   0.6< f 3/ fW< 0.8; 
   2< TTL/fW< 4.5; 
   3.8< TTL/D  max<5.2; 
   7 mm< D  max<12 mm; 
   2.9< fT/D 1 r 1<4.2; 
 
 wherein EPA is an area of an entrance pupil of the lens assembly, PL is a length of the reflective element, the length is equal to a length of a side of the reflective surface and the side is perpendicular to the axis, STD is a diameter of the stop, EPDX is a maximum entrance pupil interval when the entrance pupil passes through the axis, EPDY is a minimum entrance pupil interval when the entrance pupil passes through the axis, PH is a height of the reflective element, the height is equal to a length of a side of the exit surface, and the direction of the side is perpendicular to the incident surface, f2 is an effective focal length of the second lens group, f3 is an effective focal length of the third lens group, fW is an effective focal length of the lens assembly as the lens assembly is at the wide-angle end, fT is an effective focal length of the lens assembly as the lens assembly is at the telephoto end, TTL is an interval from the incident surface of the reflective element to an image plane along the direction perpendicular to the axis and the axis, Dmax is a maximum effective optical diameter among all lenses, and D1r1 is an effective optical diameter of a first side surface of a lens closest to the first side. 
 
     
     
       9. The lens assembly as claimed in  claim 1 , wherein:
 the first lens group comprises a 1-1 lens and a 1-2 lens, both of which are arranged in order from the first side to the second side along the axis; 
 the second lens group comprises a 2-1 lens, a 2-2 lens, and a 2-3 lens, all of which are arranged in order from the first side to the second side along the axis; 
 the third lens group comprises a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens, all of which are arranged in order from the first side to the second side along the axis; 
 the fourth lens group comprises a 4-1 lens; and 
 the fifth lens group comprises a 5-1 lens. 
 
     
     
       10. The lens assembly as claimed in  claim 9 , wherein:
 the 1-1 lens is a meniscus lens with negative refractive power and the 1-2 lens is a biconvex lens with positive refractive power and comprises a convex surface facing the first side along the axis and another convex surface facing the second side along the axis; and 
 the 2-1 lens is a meniscus lens with negative refractive power and comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis, the 2-2 lens is a biconcave lens with negative refractive power and comprises a concave surface facing the first side along the axis and another concave surface facing the second side along the axis, and the 2-3 lens is with positive refractive power and comprises a convex surface facing the first side along the axis. 
 
     
     
       11. A lens assembly comprising:
 a first lens group which is with positive refractive power; 
 a second lens group which is with negative refractive power; 
 a third lens group which is with positive refractive power; 
 a fourth lens group which is with negative refractive power; 
 a fifth lens group which is with positive refractive power; and 
 a reflective element which comprises a reflective surface; 
 wherein the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group are arranged in order from a first side to a second side along an axis; 
 wherein a light from an object side sequentially passes through the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group to the second side; 
 wherein the reflective element is disposed between the first side and the second side; 
 wherein intervals of the lens groups are changeable, so that the lens assembly can change the effective focal length; 
 wherein the third lens group comprises a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens, all of which are arranged in order from the first side to the second side along the axis; 
 wherein the 3-1 lens is a plano-convex lens with positive refractive power and comprises a convex surface facing the first side along the axis and a plane surface facing the second side along the axis, the 3-2 lens is a biconvex lens with positive refractive power and comprises a convex surface facing the first side along the axis and another convex surface facing the second side along the axis, the 3-3 lens is a meniscus lens with negative refractive power and comprises a concave surface facing the first side along the axis and a convex surface facing the second side along the axis, and the 3-4 lens is a meniscus lens with negative refractive power and comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis; 
 wherein the fourth lens group comprises a 4-1 lens and the fifth lens group comprises a 5-1 lens; 
 wherein the 4-1 lens is a meniscus lens with negative refractive power and the 5-1 lens is a meniscus lens with positive refractive power. 
 
     
     
       12. The lens assembly as claimed in  claim 10 , wherein:
 the 1-1 lens comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis; and 
 the 2-3 lens further comprises a concave surface facing the second side along the axis. 
 
     
     
       13. The lens assembly as claimed in  claim 11 , wherein:
 the 4-1 lens comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis; and 
 the 5-1 lens comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis. 
 
     
     
       14. The lens assembly as claimed in  claim 10 , wherein:
 the 1-1 lens comprises a concave surface facing the first side along the axis and a convex surface facing the second side along the axis; and 
 the 2-3 lens further comprises another convex surface facing the second side along the axis. 
 
     
     
       15. The lens assembly as claimed in  claim 11 , wherein:
 the 4-1 lens comprises a concave surface facing the first side along the axis and a convex surface facing the second side along the axis; and 
 the 5-1 lens comprises a concave surface facing the first side along the axis and a convex surface facing the second side along the axis. 
 
     
     
       16. The lens assembly as claimed in  claim 1 , wherein the lens assembly satisfies at least one of following conditions:
   1.5< f 1/ fW< 2.5; 
   −1.1< f 2/ fW<− 0.3;
 
   0.6< f 3/ fW< 0.8; 
   −2< f 4/ fW<− 0.5;
 
   1< f 5/ fW< 3.5; 
 wherein f1 is an effective focal length of the first lens group, f2 is an effective focal length of the second lens group, f3 is an effective focal length of the third lens group, f4 is an effective focal length of the fourth lens group, f5 is an effective focal length of the fifth lens group, and fW is an effective focal length of the lens assembly as the lens assembly is at the wide-angle end. 
 
     
     
       17. The lens assembly as claimed in  claim 1 , wherein:
 the reflective element further comprises an incident surface connecting the reflective surface; 
 the incident surface faces the object side along the direction perpendicular to the axis; and 
 the lens assembly satisfies at least one of following conditions:
   2< TTL/fW< 4.5; 
   0.5< fT/TTL< 1; 
   3.8< TTL/D  max<5.2; 
   7 mm< D  max<12 mm; 
   2.9< fT/D 1 r 1<4.2; 
 
 wherein fW is an effective focal length of the lens assembly as the lens assembly is at the wide-angle end, fT is an effective focal length of the lens assembly as the lens assembly is at the telephoto end, TTL is an interval from the incident surface of the reflective element to an image plane along the direction perpendicular to the axis and the axis, Dmax is a maximum effective optical diameter among all lenses, and D1r1 is an effective optical diameter of a first side surface of a lens closest to the first side. 
 
     
     
       18. The lens assembly as claimed in  claim 12 , further comprising a stop and a shading element, wherein the stop disposed between the second lens group and the third lens group, the shading element disposed between the first lens group and the second lens group, and the shading element comprises a variable hole; wherein:
 at least one lens of the lens groups has different effective optical diameters in the short side direction and in the long side direction; 
 the second lens group, the fourth lens group, and the fifth lens group can move along the axis, and the first lens group and the third lens group are fixed to change intervals of the lens groups, so that the lens assembly can change the effective focal length; 
 the reflective element further comprises an incident surface and an exit surface and both of which are connected to the reflective surface; 
 the incident surface faces the object side along the direction perpendicular to the axis; 
 the exit surface faces the second side along the axis; and 
 the lens assembly satisfies at least one of following conditions:
   1.5< f 1/ fW< 2.5; 
   −1.1< f 2/ fW<− 0.3;
 
   0.6< f 3/ fW< 0.8; 
   −2< f 4/ fW<− 0.5;
 
   1< f 5/ fW< 3.5; 
   2< TTL/fW< 4.5; 
   0.5< fT/TTL< 1; 
   3.8< TTL/D  max<5.2; 
   7 mm< D  max<12 mm; 
   2.9< fT/D 1 r 1<4.2; 
   0.5 mm< EPA/PL< 5.5 mm; 
   0.7 mm< EPA/STD< 10 mm; 
   0.2< EPDX/STD< 2.1; 
   0< EPDY/STD< 1.5; 
   0.8< PL/EPDX< 4; 
   0.7< PH/EPDY< 3; 
 
 wherein f1 is an effective focal length of the first lens group, f2 is an effective focal length of the second lens group, f3 is an effective focal length of the third lens group, f4 is an effective focal length of the fourth lens group, f5 is an effective focal length of the fifth lens group, fW is an effective focal length of the lens assembly as the lens assembly is at the wide-angle end, fT is an effective focal length of the lens assembly as the lens assembly is at the telephoto end, TTL is an interval from the incident surface of the reflective element to an image plane along the direction perpendicular to the axis and the axis, Dmax is a maximum effective optical diameter among all lenses, D1r1 is an effective optical diameter of a first side surface of a lens closest to the first side, EPA is an area of an entrance pupil of the lens assembly, PL is a length of the reflective element, the length is equal to a length of a side of the reflective surface and the side is perpendicular to the axis, STD is a diameter of the stop, EPDX is a maximum entrance pupil interval when the entrance pupil passes through the axis, EPDY is a minimum entrance pupil interval when the entrance pupil passes through the axis, and PH is a height of the reflective element, the height is equal to a length of a side of the exit surface, and the direction of the side is perpendicular to the incident surface. 
 
     
     
       19. The lens assembly as claimed in  claim 3 , wherein at least one lens of the lens groups has different effective optical diameters in the short side direction and in the long side direction, wherein:
 the third lens group comprises a plurality of lenses and some of the lenses can be moved perpendicular to the direction perpendicular to the axis to achieve optical image stabilization; 
 the reflective element is disposed between the first side and the first lens group, and the fourth lens group can move along the axis to perform focusing; 
 the second lens group, the fourth lens group, and the fifth lens group can move along the axis, and the first lens group and the third lens group are fixed to change intervals of the lens groups, so that the lens assembly can change the effective focal length; 
 the reflective element further comprises an incident surface and an exit surface and both of which are connected to the reflective surface; 
 the incident surface faces the object side along the direction perpendicular to the axis; 
 the exit surface faces the second side along the axis; and 
 the lens assembly satisfies at least one of following conditions:
   1.5< f 1/ fW< 2.5; 
   −1.1< f 2/ fW<− 0.3;
 
   0.6< f 3/ fW< 0.8; 
   −2< f 4/ fW<− 0.5;
 
   1< f 5/ fW< 3.5; 
   2< TTL/fW< 4.5; 
   0.5< fT/TTL< 1; 
   3.8< TTL/D  max<5.2; 
   7 mm< D  max<12 mm; 
   2.9< fT/D 1 r 1<4.2; 
   0.5 mm< EPA/PL< 5.5 mm; 
   0.7 mm< EPA/STD< 10 mm; 
   0.2< EPDX/STD< 2.1; 
   0< EPDY/STD< 1.5; 
   0.8< PL/EPDX< 4; 
   0.7< PH/EPDY< 3; 
 
 wherein f1 is an effective focal length of the first lens group, f2 is an effective focal length of the second lens group, f3 is an effective focal length of the third lens group, f4 is an effective focal length of the fourth lens group, f5 is an effective focal length of the fifth lens group, fW is an effective focal length of the lens assembly as the lens assembly is at the wide-angle end, fT is an effective focal length of the lens assembly as the lens assembly is at the telephoto end, TTL is an interval from the incident surface of the reflective element to an image plane along the direction perpendicular to the axis and the axis, Dmax is a maximum effective optical diameter among all lenses, D1r1 is an effective optical diameter of a first side surface of a lens closest to the first side, EPA is an area of an entrance pupil of the lens assembly, PL is a length of the reflective element, the length is equal to a length of a side of the reflective surface and the side is perpendicular to the axis, STD is a diameter of the stop, EPDX is a maximum entrance pupil interval when the entrance pupil passes through the axis, EPDY is a minimum entrance pupil interval when the entrance pupil passes through the axis, and PH is a height of the reflective element, the height is equal to a length of a side of the exit surface, and the direction of the side is perpendicular to the incident surface. 
 
     
     
       20. The lens assembly as claimed in  claim 7 , wherein:
 the first lens group comprises a 1-1 lens and a 1-2 lens, both of which are arranged in order from the first side to the second side along the axis, wherein the 1-1 lens is a meniscus lens with negative refractive power and the 1-2 lens is a biconvex lens with positive refractive power and comprises a convex surface facing the first side along the axis and another convex surface facing the second side along the axis; 
 the second lens group comprises a 2-1 lens, a 2-2 lens, and a 2-3 lens, all of which are arranged in order from the first side to the second side along the axis, wherein the 2-1 lens is a meniscus lens with negative refractive power and comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis, the 2-2 lens is a biconcave lens with negative refractive power and comprises a concave surface facing the first side along the axis and another concave surface facing the second side along the axis, and the 2-3 lens is with positive refractive power and comprises a convex surface facing the first side along the axis; 
 the third lens group comprises a 3-1 lens, a 3-2 lens, a 3-3 lens, and a 3-4 lens, all of which are arranged in order from the first side to the second side along the axis, wherein the 3-1 lens is a plano-convex lens with positive refractive power and comprises a convex surface facing the first side along the axis and a plane surface facing the second side along the axis, the 3-2 lens is a biconvex lens with positive refractive power and comprises a convex surface facing the first side along the axis and another convex surface facing the second side along the axis, the 3-3 lens is a meniscus lens with negative refractive power and comprises a concave surface facing the first side along the axis and a convex surface facing the second side along the axis, and the 3-4 lens is a meniscus lens with negative refractive power and comprises a convex surface facing the first side along the axis and a concave surface facing the second side along the axis; 
 the fourth lens group comprises a 4-1 lens which is a meniscus lens with negative refractive power; 
 the fifth lens group comprises a 5-1 lens which is a meniscus lens with positive refractive power; 
 the lens assembly further comprise a shading element disposed between the first lens group and the second lens group, wherein the shading element comprises a variable hole, the variable hole can change dimension according to the effective focal length of the lens assembly and the variable hole is a non-circular hole; 
 at least one lens of the lens groups has different effective optical diameters in the short side direction and in the long side direction; and 
 the lens assembly satisfies at least one of following conditions:
   1.5< f 1/ fW< 2.5; 
   −1.1< f 2/ fW<− 0.3;
 
   0.6< f 3/ fW< 0.8; 
   −2< f 4/ fW<− 0.5;
 
   1< f 5/ fW< 3.5; 
   2< TTL/fW< 4.5; 
   0.5< fT/TTL< 1; 
   3.8< TTL/D  max<5.2; 
   7 mm< D  max<12 mm; 
   2.9< fT/D 1 r 1<4.2; 
 
 wherein f1 is an effective focal length of the first lens group, f2 is an effective focal length of the second lens group, f3 is an effective focal length of the third lens group, f4 is an effective focal length of the fourth lens group, f5 is an effective focal length of the fifth lens group, fW is an effective focal length of the lens assembly as the lens assembly is at the wide-angle end, fT is an effective focal length of the lens assembly as the lens assembly is at the telephoto end, TTL is an interval from the incident surface of the reflective element to an image plane along the direction perpendicular to the axis and the axis, Dmax is a maximum effective optical diameter among all lenses, and D1r1 is an effective optical diameter of a first side surface of a lens closest to the first side.